International Snow Science Workshop Proceedings - Montana State University Library

Item: Comparison of Measured and Modelled Snow Cover Liquid Water Content to Improve Local Wet-Snow Avalanche Prediction

• • Title: Comparison of Measured and Modelled Snow Cover Liquid Water Content to Improve Local Wet-Snow Avalanche Prediction

    Proceedings: International Snow Science Workshop 2016 Proceedings, Breckenridge, CO, USA

    Authors:

    • Christoph Mitterer  [ ALPsolut, Livigno, Italy ]  [ alpS, Innsbruck, Austria ]
    • Achim Heilig  [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]  [ Department of Earth and Environmental Sciences, Geophysics, Munich University, Munich, Germany ]
    • Lino Schmid  [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]
    • Alec van Herwijnen  [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]
    • Olaf Eisen  [ Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung ]  [ Universität Bremen, Bremen, Germany ]
    • Jürg Schweizer  [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]

    Date: 2016-10-02

    Abstract: Wet-snow avalanches can be difficult to forecast. However, recent studies have suggested that an index (LWCindex) related to the mean liquid water content of the entire snowpack can be used to predict the onset of periods with high wet-snow avalanche activity. Since this index has not yet been verified, we compared modeled and measured liquid water content to wet-snow avalanche activity for four winter seasons at the Dorfberg test site, above Davos, Switzerland. Using the 1-D snow cover model SNOWPACK, we simulated snow stratigraphy, the mean liquid water content and water infiltration within the snowpack. Simultaneously, we used an upward-looking ground penetrating radar (upGPR) to derive mean liquid water content of the snow cover and monitor changes in percolation depth. Measurement and simulations agreed fairly well and showed that increased wet-snow avalanche activity started when the mean liquid water content of the snowpack reached 0.01 and a significant diurnal increase in liquid water content was observed. In three out of four melt seasons, the first arrival of water at the bottom of the snowpack coincided with the onset of high wet-snow avalanche activity. Overall, these results suggest that the mean liquid water content index can be used to predict wet-snow avalanche activity. The model approach might be particularly helpful for narrowing down the period of temporary avalanche mitigation measures (e.g., preventive closures) since conditions favoring wet-snow avalanches usually persist only for a short period of time. Combined with a numerical weather prediction model, this approach may allow for effective wet-snow avalanche forecasting.

    Object ID: ISSW16_O6.01.pdf

    Language of Article: English

    Presenter(s):

    Keywords: wet-snow avalanches, avalanche forecasting, liquid water content

    Page Number(s): 125-131

    Subjects: wet snow avalanches avalanche forecasting liquid water content

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